Not even 5.2 is stable, let alone 5.3. It’s WIP, so it’s obvious things are often broken. 5.3 is going to release in half a year at soonest.
I remember what a dumpster fire nanite foliage was when I built 5.1 from source before it was released. Not only that, it was actually quite close to final release. Yet, when the final 5.1 came, the nanite foliage worked pretty d.a.m.n well all things considered.
I mean just half a year prior to that, most of us thought nanite with non-opaque meshes was a problem that will take years to figure out, yet it took Epic just a single release.
There can be so many things at play. The developer working on lumen can have some default variables changed to debug, so for example lumen may not be doing any ray intensity clamping in that build because the developer was in the middle of making some comparisons to the path tracer and wanted to remove the bias.
Building the latest engine from source from time to time is fine, to see what’s being cooked. But drawing any conclusions about how the features are going to work and perform in the final release based on build that is a month away from release, let alone half a year from release, is just crazy and pointless.